[Pc_Support] Re: ABS 8-Port, 5-Port GbE Switch -- VSC7388, VSC7385 (Blog article)

[Bryan J. Smith]

Derek Konigsberg <octo at logicprobe.org> wrote:
> Yes, they *do* have 802.3x support.  At least according to what my
> Intel 470F switch tells me ... cut ...

Sorry, I mixed my response.  I meant the GA620 card.

> First of all, why would you pay for a layer-3 switch if you have 
> absolutely no intention/desire/need to do routing inside that
> switch?

So I can mix 1500 byte MTU and 9000 byte MTU clients.
You can_not_ mix the two on the same layer-2 network.  ;->

> Second of all, while Jumbo frames do many sense if you're trying to
> maximize GigE performance, normal-size frames also make sense for 
> interoperability.

See previous answer.  ;->

Jumbo can make a _serious_ performance boost -- especially as it
drastically cuts down on the throttling 802.3x has to do.

> One setup I could forsee would involve a jumbo-frame VLAN for
> back-end high speed communications, and a normal-frame
> VLAN for communications with 10/100Mbps end hosts.

But what if you have a half-dozen or more workstations using a few
servers for NFS when 300+Mbps performance is _expected_?

That's why I like to have a 8-16 port layer-3 backbone for such
servers/workstations, then "dumb" desktop switches for regular users
(to a GbE uplink on that backbone switch).

_Cheaper_ than most layer-2 switch stack setups -- even at
refurb/used costs.  ;->

> With my setup, the only reason I'm really not yet doing jumbo
> frames is that I'm still mostly 100Mbps.  Also, I'm using some
> of my "in the server" GigE cards more for their VLAN capabilites
> than raw performance at the moment.

I'm still kicking myself for not buying a GSM7312 refurb when I saw
it on sale for a few hundred bucks.



-- 
Bryan J. Smith     Professional, Technical Annoyance
b.j.smith at ieee.org      http://thebs413.blogspot.com
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*** Speed doesn't kill, difference in speed does ***